The present invention is related to and claims priority from Korean Patent Application Number 99-58927, filed Dec. 18, 1999, and assigned to the assignee of the present invention.
1. Field of the Invention
The present invention relates generally to a method for optimizing the efficiency of equipment and, particularly to a method and apparatus for analyzing and optimizing the efficiency of equipment used in semiconductor manufacturing. The invention further relates to a program storage device which is readable by a machine and which tangibly embodies a program for analyzing and optimizing the efficiency of equipment.
2. Background of the Invention
In manufacturing environments such as semiconductor manufacturing, it is useful to continually improve the efficiency of the manufacturing process. Such improvements in efficiency may have desired benefits including improved yield and reduced cost of manufacture, which are advantageous in the competitive semiconductor industry. One way to improve the manufacturing efficiency is by improving manufacturing equipment efficiency. The degree of efficiency of the equipment is often referred to as general equipment efficiency.
Quantitatively, the general equipment efficiency is obtained by multiplying a time operating rate by a performance operating rate. The time operating rate is defined as a ratio of the equipment running time to turn around time. The equipment running time corresponds to a time obtained by subtracting an equipment jam time from the turn around time. The equipment jam time includes a time for which the equipment stops due to breakdown, run-down, product management (PM), engineer-down, planned stop and preparation for work. Turn around time is defined as the total manufacturing time. The performance operating rate is defined as the ratio of a valuable operating time to equipment running time. A performance loss time corresponds to a time obtained by subtracting the valuable operating time from the equipment running time. The performance loss time includes momentary jam time and speed loss time.
One conventional method for managing equipment efficiency is a method based on the time operating rate. Unfortunately, this method is has limitations, especially in reducing loss. To this end, the referenced conventional method calculates the performance operating rate based on a parameter known as unit per equipment hour (UPEH). The UPEH does not incorporate dynamic manufacturing variables (for example lot size, manufacturing time and performance of equipment) so that a dynamically changing manufacturing environment cannot be accurately reflected in an effort to optimize equipment efficiency. Rather, this conventional technique bases the calculation of performance operating loss on an average of static manufacturing data. As such, analysis of detailed factors such as the type and size of a particular performance loss is difficult to achieve. Accordingly, corrective action for eliminating a corresponding loss may be difficult to perform.
As can be appreciated, the conventional techniques to improve equipment efficiency have clear limitations. What is needed therefore, is a technique which overcomes the problems and shortcomings of conventional techniques.
The present invention provides a method for analyzing and optimizing equipment efficiency which substantially overcomes one or more of the problems noted above. In an illustrative embodiment an equipment running time is subdivided into a valuable operating time component and a plurality of performance loss time components. Ideal equipment reference information reflecting dynamic manufacturing parameters is simulated, and an operational performance loss is analyzed in detail. From the analysis of the operational performance loss, priority in input of resources is determined.
Advantageously, the present invention incorporates parameters of a dynamically changing manufacturing environment in the analysis and optimization of general equipment efficiency. Moreover, performance loss is more accurately analyzed compared to conventional methods. As such, the performance operating rate is more effectively utilized in reducing performance loss.
According to another embodiment, the present invention provides a method for analyzing and optimizing an equipment efficiency. The method includes the steps of (a) subdividing an equipment running time of a provided equipment into a valuable operating item and a plurality of performance loss items and modeling the equipment running time; (b) calculating performance loss times, among the modeled performance loss items to provide basic data, the performance loss times corresponding to items independent of dynamic variables, the dynamic variables having values that change according to the operational environment of the equipment; (c) simulating the operation of the equipment using values corresponding to the dynamic variables and the basic data and calculating target values for the performance of the equipment; (d) measuring an actual equipment running time of the equipment and calculating surveyed values for the performance of the equipment, the surveyed values corresponding to the target values; and (e) comparing the surveyed values with the corresponding target values to obtain gaps, and determining priority in input of resources.
In another aspect of the present invention, a program storage device is provided which is readable by a machine and which tangibly embodies a program of instructions executable by the machine to perform the processes described herein for analyzing and optimizing an equipment efficiency.
The present invention still further provides an apparatus for analyzing equipment efficiency, including a basic data database for storing performance loss times as basic data, the performance loss times corresponding to items independent of dynamic variables, whose values change according to the operational environment of the equipment, among a plurality of performance loss items modeled with respect to a provided equipment; an equipment simulator for receiving values corresponding to the dynamic variables input by a user and the basic data from the basic data database, simulating the operation of the equipment, and calculating target values for the performance of the equipment; a surveyed value calculator for calculating surveyed values for the performance of the equipment from the measured actual equipment running time data of the equipment, the surveyed values corresponding to the target values for the performance of the equipment; and an evaluation output unit for calculating and outputting the gaps between the target values input from the equipment simulator and the corresponding surveyed values input from the surveyed value calculator.
These and other objects of the present invention will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.